New Hook
Over 350 new items
More uses for Gems
Better use for Silt
Another use for Heart Crystal
Bricks in every color
Glowing bricks
More wire colours
More traps (Possibly a flamethrower trap)
New chest, door, table and chair type
New brick/changed gold brick texture at the sky islands
New place/mineable cloud and raining cloud blocks
New alchemy plants(or possibly decoration)
New ore type(s)(may be Platinum and Tungsten)
New mushroom furniture and blocks
New cactus furniture and blocks
Sandstone bricks and walls
New banners
A campfire (for burning marshmallows)
Icy bricks and walls
Landmines
A cooking stove
A unicorn mount (hobby horse)
Possibly a time altering item
Possibly each biome tree dropping a different type of wood (Dark blue/grey wood)

Weapons and armors:

A new high damage, low fire rate gun (could be a sniper rifle)
New mage robes.
Beam Sword
New bow
At least four new guns
New pickaxe (coloration similar to adamantite)
Clentaminator
New vanity sets (pharaoh/eskimo/steampunk/pirate/…) more than 20 new
A total of 10-20 new wings
Pvp cannons
A new light disc type weapon
Possibly shields
Possibly new Vilethorn like weapon
Possibly a cactus armor
Possibly a mushroom spear and axe that leaves spinning death shrooms behind it

World:

Moss
No space biome
Water/lavafalls as decoration
Weather effects
The option for an extra large world
Hallow & Corruption changes
More decoration/changed decoration textures
Different water color in each biome
Giant trees or Possibly a new biome
Biome themed pots
An Ice/frost biome or changed snow biome with underground
Blue/ice themed chests
Possibly fruit trees

More than 5 character/world limit
Revamped Character Menu
Mobs have health bars

Game mechanism:

PvP Mechanism changed
Possibly leveling system
Walk up 1 block tiles
Half blocks
Improved team based gaming
No increase of the current maximum health

Other:

Revamped Hardmode
Over 60 aesthetic changes
More options for Alchemy (possibly cooldown reduction)
New music for the snow biome
You will start with mana
Possibly Visible accessories
Possibly More functional statues (chest)
Possibly the ability to dye your pet and armors
Possibly Teleporters
Possibly Biome changing objects
Cthulhu as in-game character. If that was not a joke.
Danger of town destruction due to invasions.
Pure PvP servers with team based objectives, including newly generated worlds with an automatically created tower on each side of the map, with players fighting each other on a CTF game mode.
Adding sloped/inclined tiles to make the world smoother.